Strains of recombinant-inbred mice were examined for their ability to give an antibody response to alpha 1,3 dextran, polyvinylpyrrolidone (PVP), and lipopolysaccharide (LPS) derived from Escherichia coli 0113; the results obtained were compared to those previously described for Type III pneumococcal polysaccharide (SSS-III). With the possible exception of the response to alpha 1,3 dextran, which tended to be linked in part to the IgCH allotype complex, genes governing the ability of mice to respond to these antigens were not linked to the major (H-2) as well as several minor histocompatibility complexes, the IgCH allotype complex, or to each other. The response to LPS appeared to be unigenic; however, several genes were found to influence the magnitude of the antibody response following immunization with alpha 1,3 dextran, PVP and SSS-III (multigenic control). BIBLIOGRAPHIC REFERENCES: Baker, P.J., Amsbaugh, D.F., Prescott, B., and Stashak, P.W.: Genetic control of the antibody response to Type III pneumococcal polysaccharide in mice. III. Analysis of genes governing the expression of regulatory T cell activity. J. Immunogenetics 3:275-286, 1976. Baker, P.J., Amsbaugh, D.F., Prescott, B., and Stashak, P.W.: Analysis of genes governing the antibody response to Type III pneumococcal polysaccharide (SSS-III). Folia Biol. 22: 407-408, 1976.